Physicochemical Measurements of Metal-beta-Diketonates. I. Vapor Pressures. Ii. Solution Thermodynamics Studies by Gas-Liquid Chromatography

摘要

The detailed physicochemical behavior of Metal-beta-diketonate complexes within gas-liquid chromatographic (GLC) columns was studied. The vapor pressures and heats of vaporization of chelates of several metals with the bidentate ligands hexafluoroacetylaetone (hfa) and heptafluorodimethyloctanedione (fod) have been measured. These results show the hfa chelates to be more volatile than the fod chelates. GLC retention data were collected for ten different chelates in three liquid phases and the heats of solution calculated for each system from the temperature dependence of the specific retention volume. Activity coefficients were calculated at 140C, 150C and 160C for each system and the excess enthalpy of mixing determined. The octahedral tris chelates showed large positive deviations from Raoult's Law in hydrocarbon stationary phases. In a fluorinated siloxane phase these chelates showed much lower positive deviations and in many cases almost ideal solution behavior. Square planar bis chelates showed negative deviations from Raoult's Law in both hydrocarbon and siloxane phases. (Author)